Micro-flow visualization of magnetic nanoparticles for biomedical applications

An investigation to measure the flow behavior of magnetic nanoparticles through a 100mm microchannel is conducted. The magnetic field is applied externally by a permanent magnet and by using a micro-PTV system it was possible to measure the flow behavior of magnetic nanoparticles at different flow rates and magnetic fields through a 100mm glass capillary. A strong dependence on both magnetic and hydrodynamic force is observed on the nanoparticles fluidic paths. Based on these in vitro studies, important parameters and issues that require further understanding and investigation are point out

Influence of Hydrogen Annealing on the photocatalytic activity of diamond supported gold catalysts

Fenton-treated diamond nanoparticles have been submitted to hydrogen reduction at 500 °C with the purpose of modifying the nature of the functional groups present on the diamond surface. The nature of the functional groups on the diamond samples was characterized by a combination of spectroscopic and analytical techniques. In particular, Fouriertransformed infrared spectroscopy, temperature-programmed desorption, and X-ray photoelectron spectroscopy (XPS) show the decrease in the population of carboxylic acids, esters, and anhydrides after hydrogen treatment. XPS also shows a decrease on the oxygen content after the hydrogen treatment of the diamond nanoparticles and lower electronegativity of the carbons as assessed by the lower binding energy values. Although Fentontreated diamond colloids in water changes the zeta potential from positive to negative values as a function of the pH, hydrogen annealing and the disappearance of the carboxyl groups determines that the zeta potential of the resulting sample remains positive in the complete pH range. Deposition of gold nanoparticles was carried out by the polyol method consisting on the reduction of HAuCl4 by hot ethylene glycol in the presence of the support. TEM analysis shows a variation of the average gold nanoparticle size that decreases after hydrogen reduction of carboxylic groups and becomes smaller for low gold loadings. The catalytic activity of the diamond supported gold nanoparticles as a function of the surface annealing treatment and gold loading was evaluated for the natural sunlight-assisted peroxidation of phenol by H2O2. It was observed that the most efficient sample was the one having lower gold nanoparticle size that was obtained for diamond samples reduced by hydrogen at 500 °C after the Fenton treatment and having low gold loading (0.05 wt %). Turnover frequencies above 2400 and 940 h−1 were obtained for phenol degradation and H2O2 decomposition, respectively.Financial support by the Spanish Ministry of Economy and Competitiveness (MINECO, Severo Ochoa program and CTQ 2012-32315), Universidad Politecnica de Valencia (PAID-06-11, no 2095) and Generalitat Valenciana (Prometeo 2013/014 and GV/2013/040).Navalón Oltra, S.; Sempere Aracil, D.; Alvaro Rodríguez, MM.; García Gómez, H. (2013). Influence of Hydrogen Annealing on the photocatalytic activity of diamond supported gold catalysts. ACS Applied Materials and Interfaces. 5(15):7160-7169. https://doi.org/10.1021/am401489nS7160716951